500 Dr. Davy’s observations and experiments 
The air collected from the pleura had not the least foetor, 
nor indeed any smell. It extinguished flame, and was not 
inflammable. Examined by means of lime-water and phos- 
phorus (which was sublimed in it without effect,) 100 parts 
of it were found to consist of 8 carbonic acid gas, and 92 
azotic gas. 
Whence this air was derived became a question for consi- 
deration. Reflecting on the communication, discovered by 
dissection, between the pleura and the atmosphere through 
the medium of the lung, it seemed almost demonstrated, that 
the air was atmospheric air altered. 
The next question that presented itself was, how the altera- 
tion had taken place ; what had become of the oxygene that 
had disappeared ; whence the carbonic acid gas with which 
the azote was mixed ? 
To endeavour to learn how the oxygene had disappeared, 
the following experiment was instituted. The right pleura 
of a dog was inflated with atmospheric air by means of a 
double bellows, and the incision through which the air was 
introduced was closed by a suture. At the end of 48 hours 
the dog was killed. An hour after death the pleura was 
punctured under water, and about 8 cubic inches of air were 
collected, which, examined by means of lime-water and 
phosphorus, were found to contain slight traces of carbonic 
acid gas, and to consist of 93 parts azotic gas, and 7 
oxygene gas. The wound in the pleura was closed by 
coagulable lymph, and the pleura was found free from in- 
flammation. 
The result then of this experiment seems to show, that the 
oxygene was absorbed in a greater proportion than the azote ; 
